Quite a significant event took place in the USA: the Federal Communications Commission (FCC) revealed plans for abolishing the principle of net neutrality, legislatively mandated two years before. The public comment system of the Commission website was rendered inoperative for about a day and eventually was completely disabled as a result of a massive attack. The reason for the crash remained unclear: it was either an invasion of the opponents of net neutrality, who were flooding the system with identical comments, or, on the contrary, an attack launched by the supporters of net neutrality, who tried to prevent their adversaries from flooding the FCC website with fake comments.

And yet, money remains the driving force of DDoS attacks. The growing interest in cryptocurrencies led to an increase in their exchange-value in the second quarter of 2017, which in turn drew the attention of cybercriminals. The largest bitcoin exchange, Bitfinex underwent an attack at the same time as the trading of a new IOT-currency IOTA was launched. Somewhat earlier the BTC-E exchange stated that its services were slowed down because of a powerful DDoS attack. Apparently, this way cybercriminals attempt to manipulate the currency rates, which can be quite easily achieved considering the high volatility of cryptocurrencies.

Owners of DDoS botnets do not limit themselves to renting out their computing powers. At the end of June, there was registered a large-scale attempt of extortion under threat of a DDoS attack. The group that calls itself Armada Collective demanded about $315,000 from seven South Korean banks in exchange for not disrupting their online services. According to a Radware report, this was not the first case of extortion through a DDoS attack initiated by this group.

With growing financial losses from DDoS attacks law enforcement agencies begin to take the attack initiators more seriously. In April 2017 in Great Britain, a young man was sentenced to two years in prison for a series of attacks, which he had carried out five years before while still being a student. The man had created the Titanium Stresser botnet and traded its services on a darknet, thus yielding a profit of approximately £386,000.

The most infamous attack of the second quarter became a DDoS attack on Skype servers. Many users of the messenger all over the world experienced connectivity problems. The responsibility for the campaign was claimed by CyberTeam, but its motives remain unknown.

Quarter Trends

Ransom DDoS

The trend of extorting money under threat of DDoS attacks is becoming more prominent during this quarter. This approach was dubbed “ransom DDoS”, or “RDoS”. Cybercriminals send a message to a victim company demanding a ransom of 5 to 200 bitcoins. In case of nonpayment, they promise to organize a DDoS attack on an essential web resource of the victim. Such messages are often accompanied by short-term attacks which serve as demonstration of the attacker’s power. The victim is chosen carefully. Usually, the victim is a company which would suffer substantial losses if their resources are unavailable.

There is another method as opposed to the above-mentioned one: hoping to gain revenue quickly and without much effort cybercriminals contact a great number of companies by sending out ransom messages with threats of launching a DDoS attack, not taking into account the specifics of these companies’ operation. In most cases, they do not launch a demonstrative attack. Paying the ransom would create a certain reputation for a company and provoke further attacks of other cybercriminal groups.

It should be noted that these groups now are more and more represented not by well-coordinated hacker professional teams but by beginners who do not even possess the skills to launch a DDoS attack and only have the means for a “demonstrative attack”. Those who fall victim to this scheme are companies that for one reason or another have no resources to organize security for their services yet capable of parting with available funds in order to pay the ransom.

SambaCry

There is yet another important event of the quarter, which is the discovery of a vulnerability in the Samba network software. The vulnerability allows cybercriminals to execute code remotely on devices running Linux and Unix. Samba is a software suite that allows addressing network disks and printers and runs on a majority of Unix-like operating systems, such as Linux, POSIX-compatible Solaris and Mac OS X Server and various BSD OSes.

According to the Samba company, “all versions of Samba from 3.5.0 onwards have a remote code-execution vulnerability, allowing a malicious client to upload a shared library to a writable share, and then cause the server to load and execute it”.

The total number of devices with the vulnerable software reaches over 500,000, roughly estimated. This means that cybercriminals can use the devices to create botnets with the goal of carrying out large-scale DDoS attacks.

Statistics for botnet-assisted DDoS attacks

Methodology

Kaspersky Lab has extensive experience of combating cyber threats, including DDoS attacks of various complexity types and ranges. The experts of the company have been tracking the actions of botnets by using the DDoS Intelligence system.

Being part of the Kaspersky DDoS Prevention solution, the DDoS Intelligence system is intended to intercept and analyze commands sent to bots from command-and-control servers and requires neither infecting any user devices nor the actual execution of cybercriminals’ commands.

This report contains DDoS Intelligence statistics for the second quarter of 2017.

In the context of this report, it is assumed that an incident is a separate (single) DDoS-attack if the interval between botnet activity periods does not exceed 24 hours. For example, if the same web resource was attacked by the same botnet with an interval of 24 hours or more, then this incident is considered as two attacks. Also, bot requests originating from different botnets but directed at one resource count as separate attacks.

The geographical locations of DDoS-attack victims and C&C servers that were used to send commands are determined by their respective IP addresses. The number of unique targets of DDoS attacks in this report is counted by the number of unique IP addresses in the quarterly statistics.

It is important to note that DDoS Intelligence statistics are limited only to those botnets that have been detected and analyzed by Kaspersky Lab. It should also be noted that botnets are just one of the tools for performing DDoS attacks; thus, the data presented in this report do not cover every single DDoS attack occurred during the indicated period.

Q2 summary

The resources in 86 countries were attacked in Q2 2017, 14 countries increase over the Q1 2017.

Just as in Q1, almost one-half of the attacks (47.42%) were aimed at the targets in China.

China, South Korea, and the USA remained leaders by both the number of attacks and the number of targets. According to the number of reported C&C servers, the same countries are in the TOP 3; but South Korea took the first place this time.

The long-term DDoS attacks made it back in Q2. The record duration was 277 hours, which was a 131% increase compared to Q1. At the same time, the share of the attacks that lasted less than 50 hours remained practically unchanged (99.7% in Q2 vs. 99.8% in Q1).

There was a considerable drop in the share of attacks over TCP (down to 18.2% from 26.6%) and ICPM (down to 7.3% from 8.2%). This caused a rise in the percentage of SYN floods and attacks over UDP and HTTP.

Linux botnets recovered from the decline of their share in Q1. Those botnets were responsible for 51.23% of attacks in Q2 compared to 43.40% in Q1.

Geography of attacks

DDoS attacks were registered in 86 countries in Q2, where the largest number of the attacks were aimed at China (58.07% of all of the attacks), which is 3 p.p. higher compared to the previous quarter. South Korea went down from 22.41% to 14.17% and retained second place nonetheless, while the USA rose from 11.37% up to 14.03%, almost catching up with South Korea.

The top 10 accounted for 94.60% of attacks and included Italy (0.94%) and Netherlands (0.84%), pushing down Vietnam and Denmark in Q2. Russia (1.23%) lost 0.37 p.p., moving down from fourth to sixth place, while Great Britain went up from 0.77% to 1.38%, a rise from seventh to fifth place.

Distribution of DDoS attacks by country, Q1 2017 vs. Q2 2017

95.3% of the attacks were aimed at targets in the countries of top 10 in Q2 2017.

China maintained its leading position in distribution by number of targets: 47.42% of them were located in the territory of the country, a fall of 0.36 p.p. compared to Q1. At the same time, the USA pushed down South Korea by going up from third to second place. Respectively, the USA rose to 18.63% (vs. 13.80% in Q1), while South Korea went from 26.57% down to 16.37%.

The share of targets located in the territory of Russia dropped from 1.55% in Q1 to 1.33% in Q2, pushing Russia down from fifth to seventh place. Vietnam and Denmark left the top 10 and were replaced by Italy (1.35%) and Australia (0.97%).

Dynamics of the number of DDoS attacks

The number of attacks per day ranged from 131 (April 17) to 904 (April 13) in Q2 2017. The peak numbers were registered on April 24 (581), May 7 (609), June 10 (614), and June 16 (621). A relative downturn was registered on April 14 (192), May 31 (240), and June 23 (281).

Dynamics of the number of DDoS attacks in Q2 2017**Since DDoS attacks may continuously last for several days, one attack may be counted several times in the timeline, i.e., once per day.

Monday stayed as the quietest day for DDoS attacks (11.74% of all of the attacks) in Q2 2017, while Sunday became the busiest day (15.57%) on account of the activity slacking on Saturday, a fall from 16.05% in Q1 to 14.39% in Q2. Thursday became the second busiest day, coming right behind Sunday (15.39%).

Distribution of DDoS attacks by day of the week

Types and duration of DDoS attacks

SYN floods partially recovered their positions lost during the previous quarter, rising from 48.07% to 53.26% in Q2 2017. There was an increase of percentage for both UDP attacks (from 8.71% up to 11.91%) and HTTP attacks (from 8.43% up to 9.38%). At the same time, the share of TCP DDoS attacks plummeted from 26.62% down to 18.18%, while the popularity of ICMP attacks slightly decreased from 8.17% down to 7.27% (out of all of the registered attacks).

Distribution of DDoS attacks by type

Long-term attacks made it back to the statistics in Q2 2017: 0.07% of the attacks lasted more than 100 hours, while the record attack continued for 277 hours, 157 hours longer than the record of the previous quarter. At the same time, the share of attacks that lasted 4 hours or less increased from 82.21% in Q1 to 85.93% in Q2. Thus, the percentage of attacks lasting from 5 to 49 hours decreased.

Distribution of DDoS attacks by duration (hours)

C&C servers and botnet types

The top 3 countries with the greatest number of detected C&C servers was slightly changed in Q2: China retained the third place with its 7.74%, ousting Netherlands, which moved down to fourth place despite an increase from 3.51% to 4.76%. South Korea kept its leading position and saw a fall from 66.49% down to 49.11%, while the USA still retained the second place (16.07%). The top 3 countries accounted for 72.92% of C&C servers in total.

The top 10 included Canada and Denmark (each at 0.89%), ousting Romania and Great Britain in Q2. Compared to Q1 2017, there was a significant decrease in the shares of Hong Kong (down to 1.19% from 1.89%) and Russia (down to 2.68% from 3.24%).

Distribution of botnet C&C servers by country in Q2 2017

Distribution by operating system became almost balanced in Q2: the share of Linux-based botnets comprised 51.23%; accordingly, Windows-based botnets comprised 48.77%.

Correlation between Windows- and Linux-based botnet attacks

Conclusions

There were no particular changes in the statistics of the second quarter of 2017 when compared to the previous quarter. As before about one half of DDoS attacks still originated in China, also in China was one half of the detected attack targets.

The second quarter quite clearly showed that the DDoS-attack threat is perceived rather seriously. Some companies were prepared to pay cybercriminals literally after their first demand without waiting for the attack itself. This set off a whole new wave of fraud involving money extortion under threat of a DDoS attack, also known as “ransom DDoS”. The gravity of the situation can be seen in the cybercriminals’ frequent disregard for demonstrating their capabilities; instead, the fraudsters would just send out ransom messages directed at a large pool of addresses. Certainly, the “entry threshold” for ransom DDoS is extremely low, fraudsters need neither significant resources nor technical skills or knowledge.

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